Which requires more work lifting a 50 kg sack vertically

Quiz #1, Ch. 1,4

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MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1) Which of the following is a scientific hypothesis? 1) A) The Moon is made of green cheese. B) There are parts of the universe that will never be found by man. C) There are things we will never know about. D) Matter is filled with undetectable particles. E) none of the above

2) The synthesis of a large collection of information that contains well-tested and verified hypotheses about certain aspects of the world is known as a scientific

2)

A) theory. B) hypothesis. C) fact. D) law or principle. E) none of the above

3) In science, facts 3) A) are absolute. B) mean very little. C) may change. D) are more important than theories.

4) Science, art, and religion do not contradict one another because 4) A) if you choose science, you can forget about religion and art. B) if you choose religion and art, you can forget about science. C) all three have different domains. D) if you choose the right one, you can forget the other two.

5) If you push for an hour against a stationary wall, no work is done 5) A) at all. B) on the wall. C) both A and B D) none of the above

6) If you push an object twice as far while applying the same force, you do 6) A) four times as much work. B) twice as much work. C) the same amount of work.

7) If you push an object just as far while applying twice the force, you do 7) A) four times as much work. B) twice as much work. C) the same amount of work.

8) If you push an object with twice the work input for twice the time, your power input is 8) A) twice as much. B) the same amount as for half the work in half the time. C) four times as much.

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9) A job is done slowly, while an identical job is done quickly. Both jobs require the same amount of work, but different amounts of

9)

A) energy. B) power. C) both A and B D) none of the above

10) If you do work on an object in half the time, your power output is 10) A) twice the usual power output. B) half the usual power output. C) the same power output.

11) If you exert 1 N for a distance of 1 m in 1 s, you will deliver a power of 11) A) 2 W. B) 1 W. C) 1/3 W. D) 3 W. E) none of the above

12) If you exert 100 J in 50 s, your power output is 12) A) 2 W. B) more than 4 W. C) 1/4 W. D) 4 W. E) 1/2 W.

13) An object is raised above the ground gaining a certain amount of potential energy. If the same object is raised twice as high, it gains

13)

A) four times as much potential energy. B) twice as much potential energy. C) neither A nor B

14) When an object is lifted 10 m, it gains a certain amount of potential energy. If the same object is lifted 20 m, its potential energy gain is

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A) twice as much. B) less. C) more than four times as much. D) the same. E) four times as much.

15) A 1000-kg car and a 2000-kg car are hoisted the same distance in a gas station. Raising the more massive car requires

15)

A) less work. B) more than four times as much work. C) twice as much work. D) as much work. E) four times as much work.

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16) An object that has kinetic energy must be 16) A) falling. B) at an elevated position. C) moving. D) at rest. E) none of the above

17) An object that has potential energy may have this energy because of its 17) A) acceleration. B) momentum. C) speed. D) location. E) none of the above

18) Bullets are fired from an airplane in the forward direction of motion. The momentum of the airplane will be

18)

A) increased. B) decreased. C) unchanged.

19) A clerk can lift containers a vertical distance of 1 m or can roll them up a 2-m-long ramp to the same elevation. With the ramp, the applied force required is about

19)

A) half as much. B) the same. C) twice as much.

20) A bow is drawn so that it has 40 J of potential energy. When fired, the arrow will ideally have a kinetic energy of

20)

A) less than 40 J. B) 40 J. C) more than 40 J.

21) When a car is braked to a stop, its kinetic energy is transformed to 21) A) heat. B) stopping energy. C) potential energy. D) energy of motion. E) energy of rest.

22) A hydraulic press, like a simple level, properly arranged is capable of multiplying energy input. 22) A) sometimes true B) always false

23) No work is done by gravity on a bowling ball that rolls along a bowling alley because 23) A) the force on the ball is at right angles to the ball's motion. B) no distance is covered by the ball. C) no potential energy is being converted to kinetic energy. D) its kinetic energy remains constant. E) no force acts on the ball.

24) Which requires more work: lifting a 50-kg sack vertically 2 m or lifting a 25-kg sack vertically 4 m? 24) A) lifting the 50-kg sack B) lifting the 25-kg sack C) Both require the same amount of work.

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25) A 50-kg sack is lifted 2 m in the same time as a 25-kg sack is lifted 4 m. The power expended in raising the 50-kg sack compared to the power used to lift the 25-kg sack is

25)

A) the same. B) twice as much. C) half as much.

26) In raising a 5000-N piano with a pulley system, it is noted that for every 1 m of rope pulled down, the piano rises 0.1 m. Ideally, this means the force needed to lift it is about

26)

A) 5000 N. B) 50 N. C) 500 N. D) not enough information given

27) A heavy pile driver starting from rest falls on a pile with a force that depends on the 27) A) distance the pile falls. B) original potential energy of the driver. C) original height of the driver. D) all of the above E) none of the above

28) One end of a long uniform log is raised to shoulder level. An identical log is raised at its center to the same level. Raising the second log requires about

28)

A) twice as much work. B) more than twice as much work. C) the same amount of work.

29) Strictly speaking, if any electrical device in your car is turned on (such as an air conditioner, headlights, or even a radio), more gasoline is burned by the engine. This statement is

29)

A) true only if the car's engine is stopped. B) always true. C) true only if the car's engine is running. D) totally false. E) none of the above

30) A heavy and a light object released from the same height in a vacuum have equal 30) A) momenta. B) energies. C) weights. D) all of the above E) none of the above

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